Automatic telephone system



1932- w. HATTON ET AL 1,840,950

AUTOMATIC TELEPHONE SYSTEM Filed Oct. 16, 1930 s Sheets-Sheet INVENTOR WILLIAM HATTON BY ROBERT DAHL Jan. 12, 1932. w. HATTON ET AL 1,840,950

AUTOMATIC TELEPHONE SYSTEM Filed Oct. 16, 19:50 a sheets-sheet 2' INVENTO WILLIAM HA TON ROBERT DAHL Jan. 12, 1932. w. HATTON ET AL 1,840,950

AUTOMATIC TELEPHONE S YSTEM INVENTOR W|LL|AM HATTON ROBERT DAHL 06% ATTORN EY EIC Patented Jan. 12, 1932 UNITED STATES anna PATENT, OFFICE WILLIAM HATTON AND ROBERT DAHL, F PARIS, FRANCE, ASSIGNORS 'lO INTER- NATIONAL STANDARD ELECTRIC CORPORATIUIT, 01 NEW YORK, N. Y., A CORPORA- TION 0? v DELAWARE AUTOMA'IZC TELEPHONE SYSTEM Application filed October 16*, 1930, Serial No. 489,690, and in Great Britain November 15, 1929.

lnis invention relates to automatic or semiautomatic telephone systems.

One object of the invention is to provide an improved selector connector by means of "1 which an idle outgoing junction can be taken into use ora wanted local line can be reached.

lVith this object in View, one feature of the invention comprises a selector switch or switches with which is or are associated a marking switch, and which is adapted to in the selected group in accordance with the valueof a second digit.

The invention w1ll be described by way of example-with regard to two-way tie line working between small automatic exchanges comprising link circuits.

Each link circuit comprises a line finder,

one or more selector switches and a marking 1 switch, the selector switch or switches having access to local lines or outgoing junctions.

Certain of said junctions may lead to a manual exchange, while, the others are twoway tie-lines to similar automatic exchanges. Release forinter-exchange calls is in the hands of the callingsubscriber. In order to prevent a called subscriber held condition, back release is provided after a certain time if I the calling subscriber holds after the called subscriber has hung up. During the back release the incoming end of a tie line becomes freed before the outgoing end and it is therefore possible for a new call to be originated at the distant exchange over the said tie line before the other end of the tie line is released.

Another object of the present invention is to allow such a call. to proceed and a new connection to be established without interfering with the release of the previous connection.

i" ith this object in view another feature of the present invention consists of a bothway junction circuit, which is adapted to be seized at one end for setting up a call while the other end is still engaged.

to subscribers while for between 50 and 100 subscriljiers two selectors in parallel will be provided, both of which are adapted to be controlled by the same marking switch. The selectors have access to local lines or to groups of junctions. I

Fig. 2 shows a two-wire tie line circuit to be provided at each end of a tie line. The two ends of the circuit appear respectively the banks of the link circuit selectors and the link circuit finders for outgoing and incoming calls respectively.

The setting up of a call from one exchange to another over a tie line will now be described.

lVhen a subscriber removes a receiver a circuit is closed for his line relay which energizes and in turn operates a starting relay to connect test potential to terminal 6 of the line finder EMF of the link circuit. The starting relay also completes a circuit for the magnet emf via its interrupter contacts causing the line finder to hunt; earth, wiper s-ml, interrupt 1 contacts of SMSl, Sci, normal contact of SMSl, Lil, Al, front contact of startrelay, jack BU interrupter contacts and wi iding of to battery. When the finder F reaches the calling line, relay Lt'oper- ZlbGo via wiper e of SMF and locks in series with relay Lt via normal contact N of SMSI to earth over the circuit previously traced. Relays L?) and A now operate in turn in obvious circuits. The dial tone starting circuit is now closed from earth at A3 over Wiper 3-7226. dial tone being sent via and A5 to th wire. Relay ope ates in series with the calling subscribers cut-oh relay to earth at A2, and line relay As then operates over the calling loop. Relay Se energizes: battery, winding of Se, make before break contactsof Se, Asl, make before break contacts of T0 line automatic rural exchange comprisand Fr contacts A6, make before break contacts 3 of M0, earth. Relay Se locks over its contacts 2, back contact of C8 and make be fore break contact 2 of R0 to earth as previously described.

The subscriber hearing dial tone, dials the first digit and the switch SM is stepped in the following circuit: earth, A82, S63, windingof dialling relay Lm, T01, winding of SM battery. immediately SM leaves normal switch SMSl begins to hunt in the following circuit: earth J 11, T02, S65, interrupter contacts of SMSI, Sal, wiper sm2, SMSl, battery. It will be noted that two diii'erent connections may be made to the contacts in the banks of wipers sml and 87725. Lead A is to beconnected to terminals corresponding to tie lines or junctions, while lead B is to be connected to the other terminals. 7 Since the call isoutgoing, SM will stop on contacts to which the leads A are connected. lVhen SMSl reaches a free junction in the group marked by SM, the relay J 25 will operate in the following circuit: earth, A3, sm6, 61, both windings of Jt in series, S'ml, C1, B4 in the tie line circuit, tobattery via a resistance. Operation. of J25 stops switch SM, and closes a circuit for relay Me as follows: battery, Mo, 80915, back contact of Lm, J t1 to earth. Relay Me releases relay As and closes a metallic circuit through the link. This relay also connects earth at its contact 3.to the low resistance left-hand winding'of Jt to busy the junction and closes a holding circuit for relay Lb. Relay Se is released by the operation of M0.

The link circuit remains in this condition through conversation.

Turning now to the tie line circuit when ing the circuit via C1, B2, for relay Mb. Re-

lays X, B, Lm in turn pulled up in obvious circuits. The tie line is normally looped from conductor a, via C02,-A5, winding of I0, C03,

to the 6 wire, relay I0 being pulled up over this loop for incoming calls: the operation of relay X breaks this circuit to prevent an incoming call taking place. Relay Is now operates over the calling loop, earth being supplied to its left hand winding at B3. Relay Lm is thereby released and the following circuit is formed forrelay T1: battery, Tl, back-contact of Lm,l81, X'l,earth; Operationof'Tl closes the calling loop to'the distant, exchange in which relay Ys operates as follows: battery, 005, right hand windings ofv Y8, 1712,15 2 to the a lead through winding'of the la relay at the incoming end of the tie line, back over the 6 lead, T13, left hand winding of Y8, C04, X2 to earth. Relay Mb holds via T14, Ys2. lVhen the link circuitat distant exchange is connected to the tie line a dialling tone is transmitted to the calling party; who then commences dialling the number of the wanted party.

fore begins to hunt immediately mined that the wanted outlet is in its banks,

On the reception of the first impulse relay T1 is released at Isl, disconnecting the calling and the transmitting circuit from the junction and completing a circuit for relay C0:

battery, C0, Ysl, T13, is t hand winding of Y8, C04, X2, to earth. Relay C0 operates and locks via its contact l, disconnects the calling circuit and prepares the conversation circuit, at 005. The slow releasing relay Lm also becomes energized during 'impulsing completion of dialling, relay Ys is energized in the following circuit: earth, left hand winding of line relay As in the distant link circuit, a lead, 152, T12, righthand winding ofYs, G05, left hand windings of Ys, T123, 6 lead right hand winding of As in the distant link circuit, battery.

Atthe distant end seizure of the tie line operated relay To in the tie line circuit. Relay 10 operates relay B in an obvious circuit and at its contacts 1 energizes the starting relay (not shown) for the link circuit finders and puts test potential on the contacts ofthe wipers e. The link circuit operates as described before up to the receptionof the tens digit. Relay C0 in the tie line circuit becomes operated in series with the relay E of the link circuit releasing relay l0. Relay B is, however, held at $01. In this case, wipers- 8ml, amt"), will stop on contacts connected to the B leads. Test relay J z? is connected via wiper sm lto battery, via a-resistance, and at its ther side't he test brush e1 ofSMSl. Level 01 is the marking level as shown and theswitch advances l0 terminalsfor each step made SM. W hen the tens impulses complete SMconies to rest and Lm de-energizes.

If the exchange has more than 50' lines the link circuit will contain 2 7 SMS switches, each of which is 50 pointswitch. Switch SM is-a 10 point switch, the first five contacts steps from its fifth to its sixth contacts the stepping circuit for SMSl is immediately broken and a steppingcircuit for the second selector 1S closed. The second selector there- 1 it is deterand SMSl is stopped in whatever position it has reached. In the present instance it will be taken that the, wanted outlet is in. the banks of SMSl, and when this switch reache the marked terminal, relay Jt will operate from battery, via wiper c'm/l, windings of iii be traced from Relay. Tc will now operate; battery Te, 81%, back contact of Lm, J :51, earth. The units impulses are received direct on SMSl, the change in the instepping circuit being effected by To. The insteppin'g circuit may ground, e32, 863, Lm, tel, 8m 2,winding of SMS'l, battery. Relay Pb operates via front contact of Lm, 8M5, T04,

Ft2,-A6, M03, earth. Relay Hs now oper-- ates in an obvious circuit and-relay R0 energizes as follows: battery, R0, back contact of R9, Pbl, CS1, R02, A6, M03, earth. Relay Rc locks via bank contact of'Rg, R02, to earth,

as before. When the last'impulse isreceived Lm de-energizes and opens the circuitfor Pb, which in turn -opens the circuit for H8, which slowly releases. The wanted line is tested during release of HS and if it is free relay F t pulls up in the following circuit:

battery, wanted subscribers cut off relay, wiper 01 of SMSl, right hand winding of Ft, H81, Pb2, back contact of Lm, sm5, T04,

.- Ft2, A6, M03, earth. F t locks over #2, be-

; circuit.

\Vhen the calling subscriber hangs up relay Is in the outgoing tie line circuit releases followed by relays Tl, Y8, Mb, X, B and C0, the outgoing circuit thereby returns to normal. After relay X has released and before relay B has de-energized, the battery in shunt on the winding of relay C is removed. Relay Jt in the link circuit therefore de-energizes followed by relay M0 and the link circuit returns to normal. The relay Tl breaks the circuit of relay, As in the local link circuit at the distant exchange. Relays Mb and X thereupon release in turn, the latter removing locking ground from all the other relays. Switch Sm now homes in a circuit via contact A4, and wiper sml. When SM reaches normal, SMSl is horned; ground sml, interrupter contacts of SMSI, S81, off normal contacts and winding of SMSl, battery; when SMSl has reached home, the test circuit for relay Lt is again complete, making the link circuit available for a new connection.

If the calling subscriber holds on after the called subscriber has hung up, timed back release takes place. 7 i

When the called subscriber hangs up his feed relay Cs de-energizes and a circuit is completed for thermostat relay TH: battery,

Th, S64, C81, R02, A6, M03, earth. Th pulls up after thirty seconds, putting battery on the ewiper of SME. Relay Br in the incoming tie-Ii-ne circuit therefore energizes, putting a direct earth on the 0 wiper and holding relays C0 and B. Relay E in the link circuit is short-circuitedand disconnects relay As, so that the link circuit releases. Relays B1, C0 and B release when the thermostat falls back, Disconnection of As in the incoming link circuit releases relay Ys in the outgoing tie-line circuit. Relays Mb, X, T1, and C0 in the said circuit also release in turn, but relays C and B remain operated. lVith X de-energized and B operated, the battery in shunt on relay C is disconnected so that'relay J t in the originating link circuit is released, followed by M0 and relay Is in'the tie-line circuit. The calling loop is now connected to relay As and since the loop is still closed, As operates. A circuit is now formed for thermostat relay Th: battery Th, Se l, 081, R02, A6, M03, earth. Relay Th operates after thirty seconds connects battery to Wiper e to energize the subscribers fault relay which grounds wiper '0 of .SMF. Relay E is de-energized to releasewthe link circuit as described above.

It will be noted, however, that the incoming end of the tie-line falls free thirty seconds before the outgoing end is released. There is therefore the possibility that a subscriber at the incomingexchange mayseize the tie-line for a call in the opposite direction before the other end of the tie-line is released. It is necessary therefore to ensurethat the initiation as such a call may take place without interfering with and without hindrance from the release operations at the other end.

If the previously described connection is referred to, it will be found that for an incoming call, firstly relays I0 and B, and later releaysCo and B are operated. Both these conditions duplieate'the forced release condition in an outgoing tie line circuit, that is, that relay X shall be released and relay B energized. Thus release is not interfered with.

Similarly the forced release conditions in an outgoing tie-line circuit consist of the energization of relays C and B only. Relay C does not interfere with the answering loop of the tie-line circuit and the operation of B is essential to an incoming call also, so that an incoming call may proceed unchecked.

lfthe calling subscriber hangs up after the thermostat at the incoming link circuit has operated, another call may be initiated in the same direction over the tie-line while relays Br, C0 and B in the incoming tie-line circuit are operated. Since C0 holds the normal answering loop open, the call cannot proceed,

but in order that the distant end of the line shallnot release, B-rcloses an alternative loop .on the tie-line at its contacts 1. \Vhen Th inthelink circuit releases, B1" and C0 release and the new call proceeds.

What is, claimed is 1. In ,an automatic telephone system, a

change junction, means for causing the juncttion to be seized at one end-fort setting up a call, before the other'end has been released from a previous connection in the same or opposite direction. j 3

2. In an automatic telephone system, a circuit arrangement for a two-way inter-exchange unction in which one end of the junction may bemade available for setting up calls while the other end is still connected up in a previous connection in the same or opposits direction. I

In anautomatic' telephone system the, combination of a calling and called subscriber-at difierent exchanges,means for extending a connection between said subscribers over a two-way inter-exchange junction, the release of the connection normally under control of the calling subscriber, means for causing a forced release to take place if the calling subscriber delays hanging up.

' 4-. In an automatic telephone system the combination of a calling and a called subscriber, means for extending a connection betweensaid subscribers over a junction, the release I of the connection is normally under the control of the calling party, and in which forced release of a connection is initiated at the called end if the called subscriber is unduly held, means whereby it the calling subscriber initiates a newcall the calling end of a junction after forced release has been initiated at the called end, the junction may be seized for the new call in the same vdirection before the incoming end of the junction has beenfreed at the other exchange; independent of the normal releasing means, and means controlled by the time relay means to render the trunk line-free ,for selection while the connection remains at one end.

8. A circuit arrangement as claimed in claim a comprising'ran, alternative holding circuit characterized in this that the circuit of the incoming call answering relay at the called; end of the junctionis held open during forced release at the called exchange, but that thealternativeholding circuit is meanwhile completed to. prevent the breaking downof a further incoming call.

In witness whereof, we hereunto subscribe our names this25th dayfof September, 1930.

ILLIAM HATTON. ROBERT DAI-IL.

5. In an automatic telephone system the combination of a calling and called subscriber, means for extending a connection between said subscribers, means whereby the release of'the connectlon 1s normallv under control of the calling party, and in which forced release by a called subscribe'ris controlled-by time delay means.

combination of a calling and called line, a

' 6. In a telephone exchange ,system' the selector switch having access to a group of outlets, a marking switch for marking said outlets to render them selectable by said selector switch to extend a connection from the calllng to the called line, means for releasing said connection normally under control of the calhng l1ne1,'and a time delay means for releasing said connection independent of the normal releasing means.-

7 7. In a telephone exchange system the combination of a plurality of exchanges connected by trunk lines, a selector and a mark- "ing switch, means controlled bysaid' selector to engage an idle trunk to extend a connection to another exchange, means normally controlled by a calling line to control the release of said connection, a time delay means for releasing the connection and controlled 

